| Summary: | To assess the reproducibility of the ocular response analyzer (ORA) in
nonoperated eyes and the impact of corneal biomechanical properties on
intraocular pressure (IOP) measurements in normal and glaucomatous eyes. METHODS:
In the reliability study, two independent examiners obtained repeated ORA
measurements in 30 eyes. In the clinical study, the examiners analyzed ORA and
IOP-Goldmann values from 220 normal and 42 glaucomatous eyes. In both studies,
Goldmann-correlated IOP measurement (IOP-ORAg), corneal-compensated IOP
(IOP-ORAc), corneal hysteresis (CH), and corneal resistance factor (CRF) were
evaluated. IOP differences of 3 mm Hg or greater between the IOP-ORAc and
IOP-ORAg were considered outcome significant. RESULTS: Intraexaminer intraclass
correlation coefficients and interexaminer concordance correlation coefficients
ranged from 0.78 to 0.93 and from 0.81 to 0.93, respectively, for all parameters.
CH reproducibility was highest, and the IOP-ORAg readings were lowest. The median
IOP was 16 mm Hg with the Goldmann tonometer, 14.5 mm Hg with IOP-ORAg (P <
0.001), and 15.7 mm Hg with IOP-ORAc (P < 0.001). Outcome-significant results
were found in 77 eyes (29.38%). The IOP-ORAc, CH, and CRF were correlated with
age (r = 0.22, P = 0.001; r = -0.23, P = 0.001; r = -0.14, P = 0.02,
respectively), but not the IOP-ORAg or IOP-Goldmann. CONCLUSIONS: The ORA
provides reproducible corneal biomechanical and IOP measurements in nonoperated
eyes. Considering the effect of ORA, corneal biomechanical metrics produces an
outcome-significant IOP adjustment in at least one quarter of glaucomatous and
normal eyes undergoing noncontact tonometry. Corneal viscoelasticity (CH) and
resistance (CRF) appear to decrease minimally with increasing age in healthy
adults.
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